Hi,

For online signatures to work in Odoo, the core sign module is essential, along with modules related to the specific documents you're signing (e.g., sale_management, purchase). If you only receive a PDF, verify that all necessary modules are installed and that the signature request settings are correct. Pay close attention to the email template used for signature requests, ensuring it includes the correct placeholders (like {{ object.access_url }}) and is set to HTML content type.

Also, check the system parameters, particularly sign.enable_online_signature (should be True) and web.base.url (should be your Odoo instance's correct URL). Test with a simple document to isolate the issue, examine Odoo logs for errors, and ensure users have the correct permissions. Common problems include incorrect email templates, missing web.base.url, and unmet module dependencies. Clear your browser cache and restart the Odoo service to resolve potential caching issues. If problems persist, consider contacting Odoo support.

Hope it helps